SharpGL(Opengl)入门之纹理星球

PS：SharpGL是C#对Opengl的封装，不了解SharpGL的同学可以去www.codeproject.com搜索SharpGL。

做个小例子，能够加载各种图片到球形的星球上显示，星球自动旋转，可用WSAD和鼠标控制视角，用QE控制上下，文末附源代码和release程序。

A picture paints a thousand sentences.

PS：旋转的地球GIF在这里：http://images.cnblogs.com/cnblogs_com/bitzhuwei/482613/o_earth.gif

旋转的月球GIF在这里：http://images.cnblogs.com/cnblogs_com/bitzhuwei/482613/o_moon.gif

1 初始化材质、光照、纹理和星球

private void openGLControl_OpenGLInitialized(object sender, EventArgs e)
        {
            OpenGL gl = openGLControl.OpenGL;

            gl.ClearColor(0, 0, 0, 0);
            gl.ShadeModel(OpenGL.GL_SMOOTH);
            //初始化材质
            var mat_specular = new float[] { 1.0f, 1.0f, 1.0f, 1.0f };
            var mat_ambient = new float[] { 1.0f, 1.0f, 1.0f, 1.0f };
            var mat_diffuse = new float[] { 2.0f, 2.0f, 2.0f, 0.1f };
            var mat_shininess = new float[] { 100.0f };
            gl.Material(OpenGL.GL_FRONT, OpenGL.GL_SPECULAR, mat_specular);
            gl.Material(OpenGL.GL_FRONT, OpenGL.GL_AMBIENT, mat_ambient);
            gl.Material(OpenGL.GL_FRONT, OpenGL.GL_DIFFUSE, mat_diffuse);
            gl.Material(OpenGL.GL_FRONT, OpenGL.GL_SHININESS, mat_shininess);
            //初始化光照
            var ambientLight = new float[] { 1.0f, 1.0f, 1.0f, 1.0f };
            var diffuseLight = new float[] { 1.0f, 1.0f, 1.0f, 1.0f };    
            var posLight0 = new float[] { 2.0f, 0.1f, 0.0f, 0.0f };
            gl.Light(OpenGL.GL_LIGHT0, OpenGL.GL_AMBIENT, ambientLight);
            gl.Light(OpenGL.GL_LIGHT0, OpenGL.GL_DIFFUSE, diffuseLight); 
            gl.Light(OpenGL.GL_LIGHT0, OpenGL.GL_POSITION, posLight0);
            //初始化纹理
            texture = new SharpGL.SceneGraph.Assets.Texture();
            texture.Create(gl, "Data/earth.bmp");
            //初始化星球
            ptrBall = gl.NewQuadric();                    
            gl.QuadricNormals(ptrBall, OpenGL.GL_SMOOTH);
            gl.QuadricTexture(ptrBall, (int)(OpenGL.GL_TRUE));

            gl.Enable(OpenGL.GL_TEXTURE_2D);
            gl.Enable(OpenGL.GL_LIGHTING);
            gl.Enable(OpenGL.GL_LIGHT0);
            gl.Enable(OpenGL.GL_LIGHT1);
            gl.Enable(OpenGL.GL_DEPTH_TEST);
        }

2 绘制星球

private void openGLControl_OpenGLDraw(object sender, PaintEventArgs e)
        {
            if (this.texture != null)
            {
                OpenGL gl = openGLControl.OpenGL;

                gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT);
                
                gl.LoadIdentity();
                gl.Scale(3.6, 3.6, 3.6);//放大到3.6倍
                gl.Rotate(90, 1.0f, 0, 0);//绕X轴旋转90度
                gl.Rotate(-rotation, 0.0f, 0.0f, 1.0f);//饶Z轴旋转
                gl.Sphere(ptrBall, 1.0f, 100, 100);//绘制星球

                rotation += 3.0f;
            }
        }

3 通过OpenFileDialog替换纹理

private void lblTextureImage_Click(object sender, EventArgs e)
        {
            if (openTextureImage.ShowDialog()== System.Windows.Forms.DialogResult.OK)
            {
                UpdateTextureImage(openTextureImage.FileName);
            }
        }

        private void UpdateTextureImage(string filename)
        {
            var gl = this.openGLControl.OpenGL;
            if (this.texture != null)
            {
                this.texture.Destroy(gl);
                this.texture.Create(gl, filename);
                this.lblTextureImage.Text = (new FileInfo(filename)).Name;
            }
        }

4 通过拖拽替换纹理

4.1 属性设置

将OpenGLControl的AllowDrop属性设置为True。

4.2 事件代码

为OpenGLControl添加DragEnter和DragDrop事件。

代码如下。

private void openGLControl_DragEnter(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop))
            {
                e.Effect = DragDropEffects.All;
            }
            else
            {
                e.Effect = DragDropEffects.None;
            }
        }

        private void openGLControl_DragDrop(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop))
            {
                var item = (string[])e.Data.GetData(DataFormats.FileDrop);
                UpdateTextureImage(item[0]);
            }
        }